Lubricating composition



United States Patent 3,127,347 LUBRICATIN G COMPOSITION Raymond A.Franz, El Dorado, Ark., assignor to Monsanto Chemical Company, St.Louis, M0,, :1 corporation of Delaware No Drawing. Filed May 20, 1960,Ser. No. 30,431 4 Claims. ((31. 252-48) The present invention relates toa lubricating composition. More particularly, this invention relates tothe use of tetraalkyl ureas as lubricating compounds.

The lubricating properties of nitrogen containing compounds have beenrather extensively investigated. As a result many of these compoundshave been found to exhibit excellent lubricating properties while othershave shown very poor results.

It is then an object of this invention to provide a new and improvedlubricating composition. It is another object of this invention toprovide a new and improved lubricating composition comprised ofparticular nitrogen containing compounds. A more specific object of thisinvention is to provide a new and improved lubricating oil comprised ofa tetraalkyl urea. Another specific object of this invention is toprovide a new and improved lubricating grease comprised of a tetraalkylurea and a minor amount of a thickening agent. Still another object ofthis invention is to provide a new and improved lubricating compositioncompirsed of a tetraalkyl urea and a conventional petroleum lubricatingcomposition. Additional objects will become apparent from thedescription of the invention.

In fulfillment of these objects, it has been found that tetraalkyl ureaspossess very good lubricating properties and are especially adapted toutility as high temperature lubricants. The tetraalkyl ureas of thisinvention are represented by the formula:

wherein R R R and R represent alkyl radicals each containing at leasttwo carbon atoms, but not more than 18 carbon atoms. These ureas can beused per se as high temperature lubricants and also as the fluid basefor high temperature greases. The tetraalkyl lubricants of thisinvention are useful at temperatures ranging from 62 to 325 C. andhigher.

To facilitate understanding of the invention herein disclosed, thefollowing examples are presented. It is to be understood, of course,that these examples are in no 1 way to be construed as limiting theapplication, conditions, or operations of this invention.

EXAMPLE I A sample of 1,1-di-n-dodecyl-3,3-di-2-ethyl hexyl urea wassubjected to a standard Four Ball Wear Test. The test was carried out at1250 r.p.m. for two hours, steel on steel. The results were as follows:

Scar Diameters These low scar diameters indicate good lubricatingcharacteristics, superior to mineral oil and the more conventional hightemperature hydraulic fluids.

3,127,343 Patented Mar. 31, 1964 EXAMPLE n The following additional testwas used for determining the lubricating qualities of tetra-substitutedureas:

A -78 inch spindle with a polished, stainless steel head was placed inthe socket of a drill press which was set at 1000 r.p.m. Enough of theindicated urea was placed in a 1 oz. tin to sufiiciently cover thebottom of the tin. The rotating spindle was lowered into the tin andheld in position with a nine-pound weight attached to the horizontal barof the drill press. I he spindle was allowed to run in this position fortwo minutes, after which time it Was raised and the results of the testobserved. After each test the spindle was polished with No. 3 emerycloth. The criterion for judging the lubricating qualities of the ureasis a comparison with a General Electric silicone oil, No. 81406. Theresults of this testing of several representative tetraalkyl ureas aregiven in the following table.

Lubricating composition: Lubricating quality1,1-di-n-octyl-3,3-di-n-octadecy1 urea Good 1,1-di-nheXyl-3,3-di-n-octadecyl urea Good 1,1-di-n-butyl-3,3-di-n-octadecylurea z- Good l,l-di-n-dodecyl-3,3-di-n-octyl urea Fair1,1-di-n-dodecyl-3,3-di-2-ethylhexyl urea Fair 1,1,3,3-tetra-n-octylurea Fair G.E. silicone oil Poor EXAMPLE III Since thermal stability isnecessary for high temperature lubricants, the following test was usedto determine the amount of decomposition of several representativetetraalkyl ureas.

One gram of tetraalkyl urea was placed in a 10 x mm. test tube which wasimmersed in a metal (Woods alloy) bath. The temperature of the bath wasraised to 200 C. and maintained for 20 minutes, after which time thetemperature was raised to 250 C. for 20 minutes, and then to 300 C. for20 minutes. At five minute intervals the tubes were checked fordiscoloration and decomposition. At such intervals the vapors from thesample were tested for free amine with ammonia test paper dipped inethanol.

The results of the testing of several representative tetraalkyl ureas isgiven in the following table:

Visible Decomposition ,l-di-nbctyl-S,3-di-n-octadseyl urea,I-di-n-hexyl-3,3 di-n-oetadecyl urea ,i-din-butyl-3,3-di-n-octadecylurea- -d ,1d 1 3 Negative Negative. o Do.

Do. Do.

Do. Slight/300.

i-n-dodeeyl-3,3 di-n-octyl urea i-n-dodecyl-3,3-di2-ethy1hexyl urea 1 11 1 1 1, ,3 tetra-n-octyl urea EXAMPLE IV A grease was prepared from1,l-di-n-dodecyl-3,3-di-noctyl urea by thickening with 15 by weight offinely divided (less than 1 micron particle size) SlOg. A 1 gram sampleof this was then placed in a bicycle hearing. The conditions of the testwere 430 F. and 1800 r.p.m. The grease showed low loss, good coatingcharacteristics and no separation.

EXAMPLE V A grease was prepared from 1,1-di-n-heXyl-3,3-di-noctadecylurea by thickening with 15% by weight of finely divided (less than 1micron particle size) SiO A 1 gram sample of this was then placed in abicycle bearing. The conditions of the test were 430 F. and 1800 r.p.m.The grease showed low loss, good coating characteristics and noseparation.

To further exemplify the utility of the tetraalkyl ureas as lubricatingoils, Table I lists the viscosity index and pour point for a number ofrepresentative tetraalkyl ureas.

Table I Compound Viscosity Pour Index Point, F.

1,1,3,3 tetra ethyl urea 54 -81 1,1 d1-ethyl3,3 di-2, ethyl hexylurea... 80 80 1,1,di-n-buty1 3,3,-di-n-octyl urea 68. l 81 1,1,3,3 tetran-hexyl urea 68 69 1,1-di n-hexyl 3,3-di-n-oetyl 1111251.. 110 201,1-di-n-butyl 3,3-di-ndodeeyl urea... 129 -30 1,1-ki-2-ethyl hexyl3,3-di-n-oetyl me 91. 6 -59 1,1,3, -tetran-ootyl urea 127. +51,1-di-n-dodccyl 3,3-di-n-hexyl urea 1 136 40 1,l-din-dodoeyl3,3-di-2-ethyl hexyl urea 110. 1 -28 1,l-di-n-dodeoyl 3,3-di-n-octylurea 137. 41 +14 1,1-di-n-butyl 3,3-di-n-octadecyl urea a 139 +401,1-di-n-hexyl 3,3-di-n-octadecyl urea... 136 +25 1,1-di-n-octyl3,3-di-nbetadecyl urea 138 4 +35 The tetraalkyl urea lubricatingcompounds of this invention may be prepared by reacting a dialkylcarbamyl chloride having the formula with a dialkylamine having theformula wherein R R R and R represent alkyl radicals each containing atleast tWo carbon atoms preferably at an elevated temperature and in aninert diluent on reaction medium. The procedure for preparing the novelureas of this invention can be varied substantially. Whileequiinolecular proportions of the reactants are advantageously used,excessive quantities of either can be used if desired as dictated byeconomic or yield considerations. While it is not necessary to do so,the reaction is best carried out in the presence of an HCl-acceptor. Anyalkaline agent Which does not react to any serious degree with either ofthe reactants can be used. Tertiary alkylamines are particularly useful.

The reaction is preferably, but not necessarily, carried out in an inertdiluent or reaction medium. Aliphatic and aromatic hydrocarbons areparticularly useful in this regard.

The temperature of the reaction can be varied substantially. Elevatedtemperatures in the range of from about 50 C. to 200 C. are preferred.

When it is desired to use the tetraalkyl urea lubricants disclosedherein as lubricating greases, any conventional thickening agent may beused. Several non-limiting examples of such thickening agents are SiOcalcium base soap, sodium base soaps, etc. As illustrative of the use lof soap thickening agent, with the tetraalkyl lubricants at 235 F. asodium base grease made with 1,1-d-i-n octyl- 3,3-di-n-octadecyl ureaperformed just as Well as a sodium base grease made from a commerciallube oil.

The amount of thickening agent will be dependent upon the agent employedand the thickness desired for the grease. :In the practice of thepresent invention, no thickening agent is necessary, although if used,an amountof thickening agent of from 5 to 20% by weight is preferred,although more or less may be used.

The lubricants of this invention may find utility in a host ofapplications. Several non-limiting examples of applications arelubricating oils, lubricating greases, hydrau'lic fluids or in any otherutility requiring compounds having the physical characteristics setforth in the examples.

The lubricating compositions of this invention can be used in admixturewith petroleum lubricating oils and greases. These tetraalkyl ureas maybe present in such mixture in quantities ranging from 1 to percent byWeight. By addition of tetraa'lkyl lubricants to petroleum lubricants,certain properties of the petroleum lubricants may be improved.

What is claimed is:

1. A lubricating grease consisting essentially of a major amount of atetraalkyl urea having the formula wherein R R R and R represent alkylradicals containing at least 2 carbon atoms and not more than 18 carbonatoms, thickened to grease-like consistency with a minor amount of athickening agent.

2. A lubricating grease as described in claim 1 wherein the urea is1,1-di-n-dodecyl-3,3-d-i-n octyl urea.

3. A lubricating grease as described in claim 1 wherein the urea is1,1-di-n-'heXyl-3,3-di-n-octadecyl urea.

4. A lubricating grease as described in claim 1 wherein the minor amountof a thickening agent is a minor amount of SiO References Cited in thefile of this patent UNITED STATES PATENTS 1,437,027 Tanberg Nov. 28,1922 2,050,582 Orthner et al Aug. 11, 1936 2,195,167 Egerton Mar. 26,1940 2,257,717 Olin Sept. 30, 1941 2,276,696 Olin Mar. 17, 19422,668,758 Roos Feb. 9, 1954 2,710,841 Swakbn et a1. June 14, 1955FOREIGN PATENTS 17,501 Great Britain Feb. 11, 1915 802,941 Great BritainOct. 15, 1958

1. A LUBRICATING GREASE CONSISTING ESSENTIALLY OF A MAJOR AMOUNT OF ATETRAALKYL UREA HAVING THE FORMULA